There are many applications where it is desirable to connect two pipes together. One common application is vehicle exhaust systems. In vehicle exhaust systems, two pipes are often connected at a “lap joint.” A “lap joint” is formed by inserting the end of one pipe into the end of another pipe such that the ends overlap one another. A clamp is then placed around the overlapped ends of the pipes. The clamp preferably functions to seal the lap joint and to mechanically connect the two pipes together such that the two pipes are prevented from being pulled apart. Clamps are also used on other types of vehicle exhaust components such as mufflers, catalytic converters, particulate filters, nitric oxide traps, etc.
Numerous patents exist relating to clamps used for vehicle exhaust systems. Some example patents related to this field include U.S. Pat. No. 4,312,526 to Cassel, U.S. Pat. No. 4,813,720 to Cassel, U.S. Pat. No. 6,116,659 to Wagner, U.S. Pat. No. 4,790,574 to Wagner et al. and U.S. Pat. No. 5,116,083 to Gillingham et al. The clamps disclosed in the above-identified patents are each made of a relatively thin, wide strap of ductile metal and are often referred to as “wide-band clamps.” Other example patents relating to this field include U.S. Pat. No. 6,305,054 to Imes et al., and U.S. Pat. No. 4,558,891 to Wagner et al., both of which are hereby incorporated by reference in their entireties. The '054 patent and the '891 patent disclose clamps of the type often referred to as “narrow-band clamps.” Narrow-band clamps are typically more narrow and substantially thicker than their wide-band counterparts.
Narrow-band clamps typically include a cylindrical strap having opposed ends separated by a gap. A fastener such as a bolt extends across the gap. To tighten the clamp about a pipe, a nut is threaded on the bolt causing the opposing ends of the strap to be drawn together thereby closing the gap. As the opposing ends of the strap are drawn together, it is sometimes possible for a portion of the pipe being clamped to pucker and become pinched into the gap. If the clamp is being used to seal a lap joint, this puckering and pinching action provides a possible area of leakage. A number of pipe clamps currently on the market from a number of different manufacturers have this problem.